Semiconductor substrate, substrate inspection method, semiconductor device manufacturing method, and inspection apparatus

ABSTRACT

A semiconductor substrate inspection method includes: generating a charged particle beam, and irradiating the charged particle beam to a semiconductor substrate in which contact wiring lines are formed on a surface thereof, the contact wiring lines of the semiconductor substrate being designed to alternately repeat in a plane view so that one of the adjacent contact wiring lines is grounded to the semiconductor substrate and the other of the adjacent contact wiring lines is insulated from the semiconductor substrate; detecting at least one of a secondary charged particle, a reflected charged particle and a back scattering charged particle generated from the surface of the semiconductor substrate to acquire a signal; generating an inspection image with the signal, the inspection image showing a state of the surface of the semiconductor substrate; and judging whether the semiconductor substrate is good or bad from a difference of brightness in the inspection image obtained from the surfaces of the adjacent contact wiring lines.

CROSS REFERENCE TO RELATED APPLICATION

This application claims benefit of priority under 35USC §119 to Japanesepatent application No. 2006-104289, filed on Apr. 5, 2006, the contentsof which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor substrate, a substrateinspection method, a semiconductor device manufacturing method, and aninspection apparatus.

2. Related Background Art

In an in-situ defect inspection in a hole formation process of themanufacture of a semiconductor device, a defect inspection method isused, which comprises acquiring potential contrast images of thesurfaces of wiring lines present in one particular chip within thesurface of a wafer and comparing the potential contrast images of thesurfaces of wiring lines corresponding to the above wiring lines betweenadjacent cells or dies in order to detect defects of the wiring lines(e.g., Japan Society for the Promotion of Science, 132nd committee, 24thLSI testing symposium/2004, “Line monitoring method by potentialcontrast defect detection, P77-83”, Microlithography Proceedings of SPIEVol. 5752(2004), pp. 997-1008/“Develoment of voltage contrast inspectiontechnique for line monitoring 300 mm ULSI hp 90 logic contact layer”).

Defect inspection methods of this type are generally called acell-to-cell image comparison inspection method and a die-to-die imagecomparison inspection method. The cell-to-cell image comparisoninspection method is used to inspect a die such as a memory devicehaving repetitive wiring lines. While the die-to-die image comparisoninspection method is used to inspect a die such as a logic device havingno repetitive wiring lines. Conventionally, an electron beam isirradiated to the surface of such a semiconductor device to acquire apotential contrast image, and from this image, critical defects(breaking of a wire and a short circuit of the wiring line) whichpresent in a lower layer of the wiring line are detected by watching adifference in potential contrast in the surfaces of the wiring lines.

However, for example, in the case of a defective product having a highleak current value (leak current value: ˜E-5A) in which there is a shortcircuit between adjacent contact holes due to the presence of a void inan insulating film between these contact holes (hereinafter referred toas a “short between contact wiring lines”.), there is no difference ofsignal intensity between the image of this defective product and theimage of a nondefective product, so that it is impossible for theinspection method described above to judge the short as a defect fromthe value of a difference between the signal intensities, causingdifficulty in inspection. The reason is as follows: the contact wiringlines have direct or indirect electric conduction to a substrate at thebottoms of the contact holes even in the case of the defective product(the short between the contact wiring lines) (e.g., resistance value:10Ω or less), and the contact wiring lines have direct or indirectelectric conduction to a substrate at the bottoms of the contact holesin the comparative nondefective product as well (e.g., resistance value:10Ω or less), so that the quantity of charges on the surfaces of thecontact wiring lines is equal in the nondefective product and thedefective product. As a result, the prior arts have a problem ofdecreased inspection accuracy.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provideda semiconductor substrate comprising a test element group (TEG), thetest element group including:

a semiconductor layer;

first insulating films disposed at arbitrary intervals in a test regionon a surface of the semiconductor layer;

a second insulating film formed so as to cover the semiconductor layerand the first insulating films in the test region;

contact holes or via holes formed in the second insulating film andrepetitively formed so that the semiconductor layer and the firstinsulating films are alternately exposed; and

contact wiring lines formed of a conductive material to bury the contactholes or via holes.

According to a second aspect of the present invention, there is provideda semiconductor substrate inspection method comprising:

generating a charged particle beam, and irradiating the charged particlebeam to a semiconductor substrate in which contact wiring lines areformed on a surface thereof, the contact wiring lines of thesemiconductor substrate being designed to alternately repeat in a planeview so that one of the adjacent contact wiring lines is grounded to thesemiconductor substrate and the other of the adjacent contact wiringlines is insulated from the semiconductor substrate;

detecting at least one of a secondary charged particle, a reflectedcharged particle and a back scattering charged particle generated fromthe surface of the semiconductor substrate to acquire a signal;

generating an inspection image with the signal, the inspection imageshowing a state of the surface of the semiconductor substrate; and

judging whether the semiconductor substrate is good or bad from adifference of brightness in the inspection image obtained from thesurfaces of the adjacent contact wiring lines.

According to a third aspect of the present invention, there is provideda semiconductor device manufacturing method comprising executing asemiconductor device manufacturing process for a semiconductor substratejudged as nondefective by a semiconductor substrate inspection method,the inspection method including:

generating a charged particle beam, and irradiating the charged particlebeam to a semiconductor substrate in which contact wiring lines areformed on a surface thereof, the contact wiring lines of thesemiconductor substrate being designed to alternately repeat in a planeview so that one of the adjacent contact wiring lines is grounded to thesemiconductor substrate and the other of the adjacent contact wiringlines is insulated from the semiconductor substrate;

detecting at least one of a secondary charged particle, a reflectedcharged particle and a back scattering charged particle generated fromthe surface of the semiconductor substrate to acquire a signal;

generating an inspection image with the signal, the inspection imageshowing a state of the surface of the semiconductor substrate; and

judging whether the semiconductor substrate is good or bad from adifference of brightness in the inspection image obtained from thesurfaces of the adjacent contact wiring lines.

According to a fourth aspect of the present invention, there is providedan inspection apparatus comprising:

a charged particle beam source which generates a charged particle beamand irradiates the charged particle beam to a semiconductor substrate inwhich contact wiring lines are formed on the surface thereof, thecontact wiring lines of the semiconductor substrate being designed toalternately repeat in a plane view so that one of the adjacent contactwiring lines is grounded to the semiconductor substrate and the other ofthe adjacent contact wiring lines is insulated from the semiconductorsubstrate;

a detection unit which detects at least one of a secondary chargedparticle, a reflected charged particle and a back scattering chargedparticle generated from the surface of the semiconductor substrate toacquire a signal;

a signal processing unit which generates an inspection image with thesignal, the inspection image showing a state of the surface of thesemiconductor substrate; and

a judging unit which judges whether the semiconductor substrate is goodor bad from a difference of brightness in the inspection image obtainedfrom the surfaces of the adjacent contact wiring lines.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a sectional view showing a schematic configuration of asemiconductor substrate in one embodiment according to the presentinvention;

FIG. 2 is a block diagram showing a schematic configuration of aninspection apparatus in one embodiment according to the presentinvention;

FIGS. 3 to 6 are diagrams explaining an inspection principle on which asubstrate inspection method according to the present invention is based;

FIG. 7 is a flowchart showing a schematic procedure of the substrateinspection method in one embodiment according to the present invention;

FIG. 8 is a diagram showing one example of a two-dimensional histogramfor use in the substrate inspection method shown in FIG. 7;

FIG. 9 is a diagram showing one example of a sectional TEM image of ashort between contact wiring lines detected by the substrate inspectionmethod shown in FIG. 7; and

FIG. 10 is a diagram showing effects of the substrate inspection methodshown in FIG. 7 in comparison with a method according to a prior art.

DETAILED DESCRIPTION OF THE INVENTION

(1) Semiconductor Substrate

FIG. 1 is a sectional view showing a schematic configuration of asemiconductor substrate in one embodiment according to the presentinvention. The semiconductor substrate shown in FIG. 1 is characterizedin that it is designed and manufactured to comprise a test element group(TEG) for analyzing a short between contact wiring lines (CWs). The testelement group includes contact wiring lines (CWs) formed in contactholes or via holes. The contact holes or via holes are repetitivelyformed so that a semiconductor layer and first insulating films arealternately exposed. The contact wiring lines being formed of a metalmaterial such as W (tungsten) to bury the contact holes or via holes. Amore detailed description will be given below.

A semiconductor substrate S shown in FIG. 1 comprises a TEG whichincludes: a P-well 2 formed on a surface layer of a P-type semiconductorsubstrate; insulating films 6 provided at predetermined intervals P1 ona surface layer of the P-well 2; an N+-type impurity diffused layer 4formed on the surface layer of the P-well 2 between the insulating films6; an insulating film (e.g., SiO2) 22 formed to cover the P-well 2, theN+-type impurity diffused layer 4 and the insulating films 6; contactholes CH provided in the insulating film 22 at intervals P2; and contactwiring lines CW formed to bury the contact holes CH. The interval P2between the contact holes CH is half of the interval P1 between theinsulating films 6, and the adjacent contact holes CH are disposed sothat the N+-type impurity diffused layer 4 is exposed at the bottom ofone of the adjacent contact holes CH while the insulating films 6 areexposed at the bottom of the other. Thus, the contact wiring lines CWare formed in an alternately repetitive manner in a plane view so thatone of the adjacent contact wiring lines CW is grounded to thesemiconductor substrate via the N+-type impurity diffused layer 4 andthe P-well 2 and the other of the adjacent contact wiring lines CW isinsulated from the semiconductor substrate. In the present embodiment,the P-well 2 corresponds to, for example, a semiconductor layer, theinsulating films 6 correspond to, for example, first insulating films,and the insulating film 22 corresponds to, for example, a secondinsulating film. In addition, the P-well 2 formed on the surface layerof the P-type semiconductor substrate is explained as one example of thesemiconductor layer in the present embodiment, but this is not alimitation, and it should be understood that, for example, an N-typesemiconductor substrate may be used as one example of the semiconductorlayer.

(2) Inspection Apparatus

One embodiment of an inspection apparatus according to the presentinvention will be described with reference to FIG. 2.

FIG. 2 is a block diagram showing a schematic configuration of aninspection apparatus in the present one embodiment. The inspectionapparatus shown in FIG. 2 comprises an electron gun 51, a suppressorelectrode 53, an extraction electrode 55, a condenser lens 57, a wienfilter (top) 59, an aperture 61, a beam scanning deflector 63, a wienfilter (bottom) 65, an objective lens 67, a top (GND potential)electrode 69, a charge control electrode 71, a focus control electrode73, a substrate stage 79, a secondary electron detector 81, a signalprocessing unit 83, a control computer 85, a memory 86, a display unit(CRT) 87, and a direct-current power source 89. The electron gun 51generates an electron beam, and irradiates this electron beam as aprimary electron beam EB to the semiconductor substrate S. Thesuppressor electrode 53, the extraction electrode 55, the condenser lens57, the wien filters 59 and 65, the aperture 61, the beam scanningdeflector 63, the objective lens 67, the top (GND potential) electrode69, the charge control electrode 71 and the focus control electrode 73constitute a electronic optical system to control the size, track, focalposition, etc. of a flux of the primary electron beam EB. The controlcomputer 85 reads a file corresponding to an inspection target from arecipe file stored in the memory 86, and controls the electron gun 51and the electronic optical system via various unshown controllers,thereby carrying out an inspection. The direct-current power source 89applies a direct-current voltage to the focus control electrode 73 tocontrol the focus of the primary electron beam EB. Moreover, thedirect-current power source 89 applies direct-current voltages (positiveand negative) to the charge control electrode 71, and extracts from orpushes back to the surface of the semiconductor substrate S a secondaryelectron, a reflection electron and a back scattering electron(hereinafter simply referred to as secondary electrons, etc. Es)obtained from the surface of the semiconductor substrate S, therebycontrolling the charging state (positive charging and negative charging)of the surface of the semiconductor substrate S. The semiconductorsubstrate S including the TEG shown in FIG. 1 is mounted on thesubstrate stage 79.

The primary electron beam EB emitted from the electron gun 51 isconverged by the suppressor electrode 53, the extraction electrode 55and the condenser lens 57, and enters the Wien filter 59. The Wienfilter 59 causes the incident primary electron beam EB to travelstraight without deflection to enter the objective lens 67. Theobjective lens 67 converges the primary electron beam EB to focus theprimary electron beam EB on the surface of the semiconductor substrateS. The converged primary electron beam EB is deflected by the beamscanning deflector 63, and the semiconductor substrate S is scanned withthis primary electron beam EB.

In response to the scanning with the primary electron beam EB, thesecondary electrons, etc. Es are released from the surface of the wiringlines formed on the semiconductor substrate S, accelerated by anelectric field formed between the semiconductor substrate S and theobjective lens 67 to enter the Wien filter 65, and deflected by thisWien filter 65 and drawn into the secondary electron detector 81. Thesecondary electron detector 81 outputs a signal indicating the amount ofthe detected secondary electrons, etc. Es, and the signal processingunit 83 converts the received signal into an image signal and suppliesthe image signal to the control computer 85. The control computer 85executes predetermined processing for the image signal received from thesignal processing unit 83, and displays an image showing the state ofthe surface of the semiconductor substrate S by use of the display unit(CRT) 87. This image is called a potential contrast image because it hascontrast corresponding to a potential distribution on the surface of theTEG. From the signal intensities within the potential contrast imageobtained as described above, the control computer 85 judges by aprocedure described later whether the semiconductor substrate S isdefective or nondefective. A principle on which an inspection methodusing the inspection apparatus in FIG. 2 is based will be describedbelow.

(3) Semiconductor Substrate Inspection Method

When the primary electron beam EB is irradiated to, for example, thesurface of the insulating film 22 of the semiconductor substrate Sincluding the TEG shown in FIG. 1, the surface of the insulating film 22is charged. An emission efficiency δs of secondary electron of a siliconoxide film due to the electron beam irradiation at an incident voltageof about 900 eV is greater than 1, so that the surface of the insulatingfilm 22 is positively charged (EBδsα). Here, α is a coefficient of thesecondary electron pushed back onto the insulating film 22. It ispresumed that the electron also flows into the substrate as a leakcurrent within the insulating film 22 so that the neutralization andaccumulation of the charge in the insulating film 22 are kept inparallel. FIG. 3 shows a model of charge transfer in a nondefectiveproduct. In the nondefective product, there are repetitively arranged astructure (see CSS in FIG. 1) in which a contact wiring line CW1 isconnected to a P-type semiconductor substrate via the N+-type impuritydiffused layer 4 and the P-well 2, and a structure (see CSI in FIG. 1)in which the insulating films 6 exist at the bottom of a contact wiringline CW2. It is presumed that when the negatively charging electron beamEB is irradiated to the surface of the contact wiring line CW1 of thenondefective product so that the electric resistance of an equivalentcircuit (diode) D shown in FIG. 3 decreases (forward direction), thenegative charge can transfer to the substrate. Moreover, when thenegatively charging electron beam EB is irradiated to the surface of thecontact wiring line CW2 of the nondefective product, the resistancevalue of the contact to the substrate is much higher than the resistancevalue of the adjacent contact wiring line CW1. As a result, it isanticipated that the amount of negative charge accumulation increases asshown in FIG. 3. The transfer of the negative charge results in adifference in charge-up amount, so that the surface of the contactwiring line CW1 of the nondefective product is observed as a darkcontrast image (see a left half of an image GC1 in FIG. 4), while thesurface of the contact wiring line CW2 of the nondefective product isobserved as a bright part (see a right half of the image GC1 in FIG. 4).Thus, dark parts and bright parts are repetitively observed in thenondefective product, as shown in FIG. 4.

A model of charge transfer in a defective product is shown in FIG. 5. Inthe defective product, there is a void in the insulating film 22 betweenadjacent contact holes CH5 and CH6, and a short ST is caused between thecontact wiring lines. It is presumed that when the negatively chargingelectron beam EB is irradiated to the surface of the contact wiring lineCW5 of the defective product so that the electric resistance of theabove-mentioned equivalent circuit (diode) D decreases (forwarddirection), the negative charge can transfer to the substrate. Moreover,it is presumed that when the negatively charging electron beam EB isirradiated to the surface of the contact wiring line CW6 of thedefective product, the negative charge can transfer to the substrate viathe short ST. The transfer of the negative charge results in adifference in charge-up amount in comparison with a nondefectiveproduct, so that the surface of the contact wiring line CW5 of thedefective product is observed as a dark contrast image (see a left halfof an image GC5 in FIG. 6), while the surface of the contact wiring lineCW6 of the defective product is also observed as a dark part (see aright half of the image GC5 in FIG. 6). Thus, both of the contact wiringlines CW5 and CW6 are observed as the dark contrast images in thedefective product, as shown in FIG. 6. In this manner, a defectiveproduct can be recognized from a difference image of the potentialcontrast images obtained from the surfaces of the wiring lines in thenondefective product (a region of CW2 in FIG. 4) and the defectiveproduct (a region of CW6 in FIG. 6).

Specifically, a TEG is prepared, which is formed so that it repeats thesequence of being grounded to and insulated from a foundationsemiconductor layer, and the semiconductor substrate including such aTEG is scanned with the primary electron beam to acquire a potentialcontrast image. When the TEG is nondefective, the surface of the contactwiring line adjacent to the contact wiring line having a bright part isobserved to have a dark part and to be different in terms of contrasteven in visual observation, as shown in the potential contrast image GC1in FIG. 4. On the contrary, in the case of a defective product (e.g.,leak current value: ˜E-5A) in which there is, for example, a void in theinsulating film 22 between the adjacent contact holes and a short iscaused between the contact wiring lines CW5 and CW6, for example, asshown in FIG. 5, the charge (negative) on the surfaces of the contactwiring lines CW5 and CW6 can transfer to the P-well 2 via the shortedportion ST. Therefore, there is no difference in the amount of charge onthe surfaces of the contact wiring lines CW5 and CW6. Consequently, thesurfaces of the contact wiring lines CW5 and CW6 are visually observedto be the same in terms of contrast on the potential contrast image GC5,as shown in FIG. 6.

Thus, according to the semiconductor substrate in the presentembodiment, a defect can be recognized from the value of a differencebetween signal intensities because the difference of signal intensitiesbetween the nondefective product and the defective product is producedbetween corresponding regions within the potential contrast image. Thismakes it possible to easily inspect for a fault or defect.

One embodiment of the semiconductor substrate inspection methodaccording to the present invention will be specifically described withreference to FIGS. 7 and 8.

FIG. 7 is a flowchart showing a schematic procedure of the substrateinspection method in the present embodiment. First, the semiconductorsubstrate S to be inspected is placed onto the substrate stage 79 of thesubstrate inspection apparatus in FIG. 2 (step S1). As shown in FIG. 1,the semiconductor substrate S comprises a TEG for analyzing a shortbetween contact wiring lines in which there are repetitively arranged astructure CSS where a semiconductor layer 2 exist at the bottom of acontact hole CH and a structure CSI where the insulating films 6 existat the bottom of the adjacent contact hole.

Next, conditions of the electron beam are set in accordance with thestructure of the semiconductor substrate (step S2). The semiconductorsubstrate S used in the present embodiment has a structure including theN+-type impurity diffused layer 4, the P-well 2 and the P-typesemiconductor substrate. Therefore, taking into consideration the chargetransfer model for the short between the contact wiring lines, electrodebeam conditions including, for example, an incident voltage of about 900eV, a probe current of 60 nA and a charge control voltage of −40 V areemployed, under which the charge applied to the surface of the contactwiring line becomes a negative charge capable of transferring to theP-type semiconductor substrate.

Subsequently, the control computer 85 selects, from the memory 86, apreviously created recipe file including information on an inspectiontarget region and information necessary for the defect inspection, andstarts an inspection after the alignment of a wafer. The surface of thecontact wiring line to be inspected in the semiconductor substrate S isscanned with the primary electron beam EB while the substrate stage 79is being actuated (step S3), and the secondary electrons, etc. obtainedfrom the surface of the contact wiring line are detected to acquire apotential contrast image (step S4). The acquired potential contrastimage is processed by a cell-to-cell image comparison inspection methodor a die-to-die image comparison inspection method, and defect positioncoordinates are extracted from a difference image. The flow shown inFIG. 7 employs the cell-to-cell image comparison inspection method. Inthe present embodiment, the luminance (gradation) of an image of anondefective cell A and the luminance (gradation) of an image of adefective cell B are plotted on a two-dimensional histogram, and areference value (threshold value) for defect judgment is set in thehistogram to extract the position of a defect (steps S5 to S7).

For example, suppose that the image GC1 in FIG. 4 is the image of thecell A and that the image GC5 in FIG. 6 is the image of the cell B. Inaddition, in the two-dimensional histogram, for example, a vertical axisindicates the luminance (gradation) of the image of the cell B(defective), and a horizontal axis indicates the luminance (gradation)of the image of the cell A (nondefective), as shown in FIG. 8.

In this case, the surface of the contact wiring line CW1 of thenondefective product shown in FIG. 3 is observed as a dark part (seeFIG. 4), and the value of its luminance is, for example, 10 in gradationsequence. On the other hand, the surface of the contact wiring line CW5of the defective product shown in FIG. 5 is observed as a dark part, andthe value of its luminance is also 10 in gradation sequence. Theseluminance values are plotted on the two-dimensional histogram (a pointPa in FIG. 8, step S5).

Moreover, the surface of the contact wiring line CW2 of the cell A(nondefective) shown in FIG. 4 is observed as a bright part, and thevalue of its luminance is 120 in gradation sequence. On the other hand,the surface of the contact wiring line CW6 of the cell B (defective) inFIG. 5 is observed as a dark part, and the value of its luminance is 10in gradation sequence. These luminance values are similarly plotted onthe two-dimensional histogram in FIG. 8 (a point Pb in FIG. 8, step S5).

Furthermore, if the reference value (threshold value) for defectjudgment on the two-dimensional histogram is set by, for example, twostraight lines L1 and L2 whose original points are 0 in gradationsequence (step S6), the cell B can be extracted as a cell having thecontact wiring line containing a defect (short) because the point Pb isincluded in a point group located outside the straight lines L1 and L2.In addition, if the luminance values contain position coordinates, it ispossible to identify the coordinates of the position of the defect (stepS7). An example is shown in FIG. 9 in which the section of the cell B isanalyzed in accordance with the information on the defect positioncoordinates identified as described above. A void is produced amongcontact wiring lines CW4 to CW6 as shown in FIG. 9, such that it hasbeen confirmed that a defect due to the short between the contact wiringlines is present as indicated by the signs ST in FIG. 9.

According to the present embodiment, it is possible to achieve a defectinspection with high accuracy as described above, and also tosignificantly reduce a defect analysis cycle period (TAT: turn aroundtime).

FIG. 10 shows results of a comparison of the TATs in a hole formationprocess in the middle of the manufacture of a semiconductor devicebetween a method according to a prior art and the inspection method inthe present embodiment. As shown in FIG. 10, according to the inspectionmethod of the present embodiment, the TAT can be reduced by about onemonth (26 days) than that of the prior art.

(4) Semiconductor Device Manufacturing Method

When the semiconductor substrate according to the present inventiondescribed above is used and the semiconductor substrate inspectionmethod according to the present invention described above is used in aprocess of manufacturing a semiconductor device, a defect inspection canbe achieved with high accuracy and in a short TAT, such that thesemiconductor device can be manufactured with higher yield andthroughput.

More specifically, the semiconductor substrate is extracted perproduction lot, and a TEG in the extracted semiconductor substrate isinspected by the inspection method described above. When thesemiconductor substrate is judged as a nondefective product as a resultof the inspection, the rest of the manufacturing process is continuouslyexecuted for the whole production lot to which the inspectedsemiconductor substrate belongs. On the other hand, when thesemiconductor device is judged as a defective product as a result of theinspection and can be reworked, rework processing is executed for theproduction lot to which the semiconductor substrate judged as thedefective product belongs. When the rework processing is finished, thesemiconductor substrate is extracted from the production lot and againinspected for defect. If the extracted semiconductor substrate is judgedas a nondefective product as a result of the reinspection, the rest ofthe manufacturing process is executed for the production lot finishedwith the rework processing. In addition, when the rework processing isimpossible, the production lot to which the semiconductor substratejudged as the defective product belongs is disposed of. When the causeof the defect can be analyzed, results of the analysis are fed back to aperson in charge of designing, a person in charge of an upstream processor the like.

While some of the embodiments of the present invention have beendescribed above, it is obvious that the present invention is not limitedto the embodiments described above, and can be modified in variousmanners within the technical scope thereof and carried out. The caseshave been described in the above embodiments where the electron beam isused as a charged particle beam, but the present invention is notlimited thereto, and, for example, an ion beam can also be used as thecharged particle beam.

1. A semiconductor substrate comprising a test element group (TEG), thetest element group including: a semiconductor layer; first insulatingfilms disposed at arbitrary intervals in a test region on a surface ofthe semiconductor layer; a second insulating film formed so as to coverthe semiconductor layer and the first insulating films in the testregion; contact holes or via holes formed in the second insulating filmand repetitively formed so that the semiconductor layer and the firstinsulating films are alternately exposed; and contact wiring linesformed of a conductive material to bury the contact holes or via holes.2. The semiconductor substrate according to claim 1, wherein the contactwiring lines are provided so that one of the adjacent contact wiringlines is grounded to the semiconductor substrate and the other of theadjacent contact wiring lines is insulated from the semiconductorsubstrate, and one of the contact wiring lines is directly connected tothe semiconductor substrate at the bottom thereof or connected to thesemiconductor substrate via an impurity diffused layer formed on thesurface of the semiconductor substrate, and thereby grounded to thesemiconductor substrate.
 3. A semiconductor substrate inspection methodcomprising: generating a charged particle beam, and irradiating thecharged particle beam to a semiconductor substrate in which contactwiring lines are formed on a surface thereof, the contact wiring linesof the semiconductor substrate being designed to alternately repeat in aplane view so that one of the adjacent contact wiring lines is groundedto the semiconductor substrate and the other of the adjacent contactwiring lines is insulated from the semiconductor substrate; detecting atleast one of a secondary charged particle, a reflected charged particleand a back scattering charged particle generated from the surface of thesemiconductor substrate to acquire a signal; generating an inspectionimage with the signal, the inspection image showing a state of thesurface of the semiconductor substrate; and judging whether thesemiconductor substrate is good or bad from a difference of brightnessin the inspection image obtained from the surfaces of the adjacentcontact wiring lines.
 4. The inspection method according to claim 3,wherein the other of the adjacent contact wiring lines contacts, at thebottom thereof, first insulating films formed on the surface of thesemiconductor layer, and is thereby insulated from the semiconductorsubstrate.
 5. The inspection method according to claim 3, wherein one ofthe contact wiring lines is directly connected to the semiconductorsubstrate at the bottom thereof or connected to the semiconductorsubstrate via an impurity diffused layer formed on the surface of thesemiconductor substrate, and is thereby grounded to the semiconductorsubstrate.
 6. The inspection method according to claim 3, wherein thecontact wiring lines are formed to bury contact holes or via holesformed in a second insulating film, the second insulating film beingformed on the semiconductor substrate so as to cover the semiconductorsubstrate and the first insulating films.
 7. The inspection methodaccording to claim 3, wherein judging whether the semiconductorsubstrate is good or bad includes: acquiring a potential contrast imagefor each of different cells or dies, the potential contrast image beingan image with a contrast distribution corresponding to a surfacepotential distribution of the semiconductor substrate; calculating, assignal intensities, gradation values of pixels constituting thepotential contrast image; plotting the gradation values of the pixels ofthe potential contrast image obtained for each of the different cells ordies into a multidimensional region whose reference axes are thegradation values of the pixels in the one and other of the adjacentcontact wiring lines, thereby creating a multidimensional histogramshowing an incidence of the signal intensity at places corresponding toeach other between the different cells or dies; and drawing linesindicating a standard of defect judgment in the histogram, and judgingwhether a defect due to a fault in the formation of the contact holes orvia holes is present in the semiconductor substrate in accordance withwhether a region of the multidimensional histogram defined by the linescontains pixels of the signal intensities.
 8. The inspection methodaccording to claim 7, wherein information on position coordinates of thepixels is added to the gradation values corresponding thereto, andjudging whether the defect is present further includes outputtinginformation on coordinates of the position of the defect when the defectis present in the semiconductor substrate.
 9. A semiconductor devicemanufacturing method comprising executing a semiconductor devicemanufacturing process for a semiconductor substrate judged asnondefective by a semiconductor substrate inspection method, theinspection method including: generating a charged particle beam, andirradiating the charged particle beam to a semiconductor substrate inwhich contact wiring lines are formed on a surface thereof, the contactwiring lines of the semiconductor substrate being designed toalternately repeat in a plane view so that one of the adjacent contactwiring lines is grounded to the semiconductor substrate and the other ofthe adjacent contact wiring lines is insulated from the semiconductorsubstrate; detecting at least one of a secondary charged particle, areflected charged particle and a back scattering charged particlegenerated from the surface of the semiconductor substrate to acquire asignal; generating an inspection image with the signal, the inspectionimage showing a state of the surface of the semiconductor substrate; andjudging whether the semiconductor substrate is good or bad from adifference of brightness in the inspection image obtained from thesurfaces of the adjacent contact wiring lines.
 10. The semiconductordevice manufacturing method according to claim 9, wherein the other ofthe adjacent contact wiring lines contacts, at the bottom thereof, firstinsulating films formed on the surface of the semiconductor layer, andis thereby insulated from the semiconductor substrate.
 11. Thesemiconductor device manufacturing method according to claim 9, whereinone of the contact wiring lines is directly connected to thesemiconductor substrate at the bottom thereof or connected to thesemiconductor substrate via an impurity diffused layer formed on thesurface of the semiconductor substrate, and is thereby grounded to thesemiconductor substrate.
 12. The semiconductor device manufacturingmethod according to claim 9, wherein the contact wiring lines are formedto bury contact holes or via holes formed in a second insulating film,the second insulating film being formed on the semiconductor substrateso as to cover the semiconductor substrate and the first insulatingfilms.
 13. The semiconductor device manufacturing method according toclaim 9, wherein judging whether the semiconductor substrate is good orbad includes: acquiring a potential contrast image for each of differentcells or dies, the potential contrast image being an image with acontrast distribution corresponding to a surface potential distributionof the semiconductor substrate; calculating, as signal intensities,gradation values of pixels constituting the potential contrast image;plotting the gradation values of the pixels of the potential contrastimage obtained for each of the different cells or dies into amultidimensional region whose reference axes are the gradation values ofthe pixels in the one and other of the adjacent contact wiring lines,thereby creating a multidimensional histogram showing an incidence ofthe signal intensity at places corresponding to each other between thedifferent cells or dies; and drawing lines indicating a standard ofdefect judgment in the histogram, and judging whether a defect due to afault in the formation of the contact holes or via holes is present inthe semiconductor substrate in accordance with whether a region of themultidimensional histogram defined by the lines contains pixels of thesignal intensities.
 14. The semiconductor device manufacturing methodaccording to claim 13, wherein information on position coordinates ofthe pixels is added to the gradation values corresponding thereto, andjudging whether the defect is present further includes outputtinginformation on coordinates of the position of the defect when the defectis present in the semiconductor substrate.
 15. An inspection apparatuscomprising: a charged particle beam source which generates a chargedparticle beam and irradiates the charged particle beam to asemiconductor substrate in which contact wiring lines are formed on thesurface thereof, the contact wiring lines of the semiconductor substratebeing designed to alternately repeat in a plane view so that one of theadjacent contact wiring lines is grounded to the semiconductor substrateand the other of the adjacent contact wiring lines is insulated from thesemiconductor substrate; a detection unit which detects at least one ofa secondary charged particle, a reflected charged particle and a backscattering charged particle generated from the surface of thesemiconductor substrate to acquire a signal; a signal processing unitwhich generates an inspection image with the signal, the inspectionimage showing a state of the surface of the semiconductor substrate; anda judging unit which judges whether the semiconductor substrate is goodor bad from a difference of brightness in the inspection image obtainedfrom the surfaces of the adjacent contact wiring lines.
 16. Theinspection apparatus according to claim 15, wherein the other of theadjacent contact wiring lines contacts, at the bottom thereof, firstinsulating films formed on the surface of the semiconductor layer, andis thereby insulated from the semiconductor substrate.
 17. Theinspection apparatus according to claim 15, wherein one of the contactwiring lines is directly connected to the semiconductor substrate at thebottom thereof or connected to the semiconductor substrate via animpurity diffused layer formed on the surface of the semiconductorsubstrate, and is thereby grounded to the semiconductor substrate. 18.The inspection apparatus according to claim 15, wherein the contactwiring lines are formed to bury contact holes or via holes formed in asecond insulating film, the second insulating film being formed on thesemiconductor substrate so as to cover the semiconductor substrate andthe first insulating films.
 19. The inspection apparatus according toclaim 15, wherein the judging unit controls the charged particle beamsource, the detection unit and the signal processing unit, thereby:acquiring, for each of different cells or dies, a potential contrastimage which is an image with a contrast distribution corresponding to asurface potential distribution of the semiconductor substrate;calculating, as a signal intensity, gradation values of pixelsconstituting the potential contrast image; plotting the gradation valuesof the pixels of the potential contrast image obtained for each of thedifferent cells or dies into a multidimensional region whose referenceaxes are the gradation values of the pixels in the one and other of theadjacent contact wiring lines, in order to create a multidimensionalhistogram showing the incidence of the signal intensity at placescorresponding to each other between the different cells or dies; anddrawing lines indicating a standard of defect judgment in the histogram,and judging whether a defect due to a fault in the formation of thecontact holes or via holes is present in the semiconductor substrate inaccordance with whether a region of the multidimensional histogramdefined by the lines contains pixels at the signal intensities.
 20. Theinspection apparatus according to claim 19, wherein the judging unitadds information on position coordinates of the pixels to the gradationvalues corresponding to the pixels, and outputs information oncoordinates of the position of a defect when judging that the defect ispresent in the semiconductor substrate.